Past studies have indicated Cannabis to have anti-carcinogenic properties

Presidents Bill Clinton, George W. Bush, and Barack Obama all used it (although Clinton did not inhale). Over 17 million Americans (appr. 5.5 percent of all Americans) use it a year, including one out of ever five college students [source]. And 50 percent of Americans now think it should be legal, according to Gallup polling [source]. But marijuana, since 1938, has been illegal in the U.S.

Amid the growing calls to legalize America's favorite illegal drug, comes a study that's sure to draw mixed reactions. The research -- done by medical researchers at the University of Southern California -- suggests a correlation between smoking marijuana and testicular cancer.

Past studies have indicated there is no real correlation between alcohol -- one of America's most popular legal drugs -- and testicular cancer. However, studies have shown similar correlations [abstract] between smoking tobacco -- also a legal drug in the U.S. -- and testicular cancer. Current research has been unable to establish the method of causation for the tobacco-testicular cancer link.

Likewise, the study on marijuana users found a correlation between testicular cancer and use, but did not establish a causative route. The study suggests the body's endocannabinoid system -- which is excited by compounds in marijuana -- may be involved in raising risks of this specific cancer.

So how much do marijuana and tobacco appear (correlation) to raise the risk of testicular cancer?

The 2007 study on tobacco reveals, "The synthesis of our results suggests that smoking about a pack a day for ∼20 years increases one’s risk of testicular cancer ∼2-fold."

Likewise, the marijuana study showed nearly identical results when age and ethnicity were held constant. Smokers of marijuana were twice as likely to get a particular kind of testicular cancer -- mixed-germ cell tumors. Mixed-germ cell tumors include the often lethal non-seminona tumors. The marijuana study relied on querying the drug use history of 292 healthy adult men and 163 adult men with cancers.

II. Causation -- as With Tobacco -- is Undetermined

While causation is unclear, the study's lead author Dr. Victoria Cortessis says the risks should be takens seriously. She remarks to NBC News, "The group that is at risk for developing these tumors is overwhelmingly young men. They should be looking and paying attention to changes in their testicles anyway. The truth is, the vast majority of men who develop testicular germ-cell tumors survive them. There's still a small proportion that don't. Those guys tend to have non-seminonas, unfortunately. But also, non-seminomas require more extensive treatment, including radiation and chemotherapy."

"We're not concerned only with preventing non-seminomas so that the malignancy doesn't harm the man, but we're also concerned about the later health effects for men that may be related to the more-aggressive therapy."

Both the marijuana and tobacco studies have suggested that quitting use did not decrease risks among those who chronically used at some period in their life.

In the study, published [abstract] in the prestigious peer-reviewed journal Cancer, she and her fellow researchers write:

The findings suggest that the potential cancer-causing effects of marijuana on testicular cells should be considered not only in personal decisions regarding recreational drug use, but also when marijuana and its derivatives are used for therapeutic purposes.

Marijuana is legal for medical use in 17 states, including USC's home state of California, despite being illegal for medical use at a federal level.

III. Results are Immaterial to the Legalization Debate, but Are Important

Aside from the lack of understanding regarding the route of causation some marijuana advocates complain the findings are inconsistent with the past studies that showed that marijuana lowers the risk of certain kinds of cancers.

However, advocates need to realize that it is quite possible that marijuana lowers the risk of some cancers, while raising the risk of testicular cancer -- hence is the complex nature of the human body.

And while the study is receiving much scrutiny from the perspective of legalization, ultimately the study's impact on that issue should be immaterial. After all, the correlation observed is almost identical to that seen with tobacco smokers, yet tobacco is legal to use among those older than 18 in the U.S.

Smoking marijuana or tobacco likely raise you risk of testicular cancer, though each may provide some other benefits. [Image Source: Universal Pictures]

Part of the confusion with this particular study arises from that mediacoverage almost entirely ignores the well-known (among researchers) tobacco-testicular cancer correlation, which is eerily similar to the marijuana correlation in terms of risk rate. Thus the media commentary have mistakenly focused heavily on whether this should be an obstacle to legalization, when the tobacco correlation and the legality of tobacco show that to be a debate that's essentially been decided already.

The study -- and two previous studies before it that showed a similar testicular cancer and marijuana correlation -- is important, though as it should help medical professionals, patients, and recreational users make informed decisions when choosing to use. The message seems clear -- know there's risks of lighting up your favorite smoke, whether it's legal or illegal.

"Nowadays, security guys break the Mac every single day. Every single day, they come out with a total exploit, your machine can be taken over totally. I dare anybody to do that once a month on the Windows machine." -- Bill Gates